They block the active excretion of hydrogen cation from the guard cells. Due to presence of carbon dioxide, a rapid acidification of cytoplasm takes place leading to stomatal closure. Milbarrow(1974) has described the formation of these chemicals in the chloroplast. It moves to the stomata, where it is responsible for checking the intake of Potassium ion or induses loss of potassium ion from the guard cells.

Antitranspirants are of two types: metabolic inhibitors and film-forming antitranspirants.